A fuel pump which is controlled electronically as a function of the fuel requirement is known from DE 43 02 383 A1. Here, electrical energy is fed in a pulsed form to the fuel pump, wherein the duty cycle is changed as a direct function of a position output signal of an air mass flow rate sensor, wherein the sensor generates the signal as a function of the position of a throttle valve whose position is a measure of the fuel requirement of the internal combustion engine. This method of the regulated pulsed feeding of electrical energy is also known as pulse duration modulation. In particular, electric motors are composed of magnetic or magnetically permeable material which can have magnetostriction effects. Furthermore, they contain current-conducting electrical conductors in magnetic fields which experience a force which corresponds to electric current. If such an electric motor is regulated by means of pulse duration modulation, corresponding alternating forces act on the electrical conductors. In addition, the magnetostriction of the magnetic materials in the alternating magnetic field also brings about an alternating force effect and/or changes in dimensions of these components. Owing to the alternating force effects and the changes in dimensions, the electric motor may be mechanically excited so that sound waves are emitted into the surroundings. If the frequency of the sound waves is in the range of human hearing, the sound waves are perceived as noise. This is generally undesired.
It is therefore generally known to avoid sounds which can be heard by the human ear by selecting a frequency of the duty cycle of the pulse duration modulation outside the range of human hearing, preferably above 20 kHz.
The power loss of power switching transistors of corresponding control electronics is composed of conduction losses and switching losses. While the conduction losses are determined by the voltage drop across the component and the current, the switching losses are determined by the number of switching processes per time unit and the switched current. Depending on the operating parameters of the system to be controlled, the switching losses can significantly exceed the conduction losses. A further disadvantage is that the power loss leads to an increase in temperature of the switching electronics which is manifest as a reduction in the service life of the switching electronics.